Roller gap lubrication systems are often installed in roiling trains. These are used for the purpose of improving the surface quality of the work roll and the strip and are included in the normal equipment of a modern rolling train on which high-quality strips are to be fabricated.
The system in which water as the carrier medium and oil are mixed just upstream of the roller and applied to the work roll or backup roll and ultimately take effect in the roller gap is the most widespread owing to its simplicity. DE 10 2004 006 130 [CA 2,547,960], EP 1 399 276 [U.S. Pat. No. 7,266,984], EP 1 399 277 [U.S. Pat. No. 7,159,433], EP 0 367 967 [U.S. Pat. No. 5,090,225] and WO 2007/025682 [CA 2,618,836] disclose solutions of this type.
After a certain operating time, however, the effectiveness of the lubrication is reduced or the results of the roller gap lubrication cannot be reproduced. The lubrication effect is also often uneven over the width of the strip, which leads to problems in the movement of the strip. The cause of this is often that the piping between the oil/water mixer and the spray nozzles becomes clogged in layers as a result of saponification. Blockages of the small nozzles also occurs when particles become detached from the wails and float in front of the nozzle outlet.
A relatively large outlay on maintenance is necessary as a result of mechanical cleaning of the system or periodical rinsing of the piping between the oil/water mixer and the nozzles and blowing the nozzles clear.
JP 7016621 discloses periodically stopping the oil supply and carrying out a rinse of the nozzles with the water which is also used for forming the oil/water mixture.
JP 56139213 provides for a cleaning solution to be able to be introduced into the fluid lines as required in order to clean them.
In order to reduce the saponification of the roller gap lubrication system, particular demands are additionally made of the water quality or water analysis, which however makes water consumption considerably more expensive. In order to adapt the oil to the water quality, additives are added to the oil. These vary in their composition and effect in the different water qualities worldwide. Determining the oil composition is expensive, which along with the additives themselves ultimately has a detrimental effect on oil costs. Despite the expense, the oil is not always adapted optimally to the water used.